Soak the fish in water for 15-20 minutes or place in a colander in the sink under cold running water. Pat dry.

Preheat oven to 400F. Bring a large saucepan of lightly salted water to a boil and add the rutabaga and cook for 25-30 minutes until soft, drain well.
Return the rutabaga to the saucepan to dry completely over low heat, 1-2 minutes. Puree the rutabaga in the fook processor or pass through a food mill or potatoe ricer and return to pan. Cut the vanilla bean lengthwise in half, scrape out the seeds adn add to the mashed rutabaga (discard the bean or add it to a canister of surgar to make aromatic vanilla sugar). Gently stir the butter into the mashed rutabaga until it melts. Season with a little salt, keep warm.

Meanwhile, make a small incision ithrough the skin of each cod fillet and gently insert a rosemary sprig. Season well with salt and pepper adn rub with EVOO. PLace fish in a roasting pan and roast for about 15 minutes until the fish flakes easily. Place a large scoop of rutabaga on plate, top with fish and garnish with sprig of rosemary.